Musical instrument of the violin type



March 7, 1933.

G. EISENBERG MUSICAL INSTRUMENT OF THE VIOLIN TYPE Filed April 2, 1929 2Sheets-Sheet 1 INVENTORS GEORGE EISENBERG mm/M' ATTORNEY March 7, 1933.e. EISENBERG 1,900,489

MUSICAL INSTRUMENT OF THE VIOLIN TYPE Filed April 2, 1929 2 Sheets-Sheet2 A 54.? an :7

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lNVENTORS GEORGE EISENBERG ATTORNEY Patented Mar. 7, 1933 GEORGEEISENBEEG, F

PATENT OFFICE BROOKLYN, NEW YORK MUSICAL INSTRUMENT 0F THE VIOLIN TYPEApplication filed April 2,

This invention relates to musical instruments and has particularreference to an improvement in a stringed instrument of the violin type.

The main object of the invention is to provide a simple and efficientmeans whereby the bowing of a single stringed instrument of the violintype will result in the re-v production of a volume from such an act ofseveral times the amount of sound which would ordinarily be producedfrom the single instrument.

A further object is to produce this increased volume of tone withabsolute clarity and accuracy as to pitch and timbre of the originaltone.

A still further object is to provide a simple, compact device which canbe applied to the stringed instrument and can be quickly 20 and easilyadjusted by the musician, after which he can proceed to play it withouthaving to give further thought to the device.

Further and more specific objects, features, and advantages will moreclearly apar from the detailed description given beow taken inconnection with the accompanying drawings, which form part of the secification and illustrate one embodiment o the invention, and in which,

Fig. 1 is a plan view of the improved musical instrument,

Fig. 2 is a partial longitudinal sectional view, enlarged, showing themanner in which the electrical unit is mounted on the frame of theinstrument,

Fig. 3 is a cross section taken on the line 3-3 of Fig. 2,

Fig. 4 is a section taken on the line 4-4 of Fig. 2,

Fig. 5 is a cross section taken on the line 5-5 of Fig. 2, and,

Fig. 6 is a cross section taken on the line 66 of Fig. 2.

Description of the construction In the preferred form as at presentembodied and illustrated in the drawings, the invention is applied to amusical instrument I, of the violin type having a frame 10 provided w ththe usual neck 11. The usual 1929. Serial R0. 351,874.

belly and back are lacking and instead the frame 10 is provided withbars 12 and 13 extending from the front to the rear of the frame 10respectively at the top and the bottom thereof. The upper bar 12 isreinforced with a dependent flange 14 as shown. A cross bar 15 is alsoprovided. The instrumentis provided with the usual strings 16 fastenedat one end to the tail piece 17 and passing over the bridge 18 mountedon the upper bar 12.

Fastened rigidly to the top of the bridge by lock nuts 19 and 20 is arod 21 acting as transmitter of vibrations from the strings 16 throughthe bridge 18. This rod extends outwardly for a short distance and thendownwardly through a hole 22 in the upper bar 12, clearing this hole 22without contact therewith. At its lower end it is bent outwardly againand extends rearwardly of the frame and its outer end lies freely withina central bore or opening in a magnet coil 23. At the lower portion ofthe rod 21 Where it bends outwardly, it is engaged by a flexible membersuch as a cat-gut string or cord 24 which is Wrapped around a shaft 25.The other 75 end of the shaft 25 has a worm wheel 26 meshing with a wormgear 27 on a shaft 28 to the upper end of which is fastened a thumbpiece 29 by turning which the tension and position of the vibrationmember or rod 21 can be regulated through tightening or loosening thecat-gut.

The electrical unit which is affected by the vibrations of the member orrod 21 comprises a horse-shoe magnet 30. Beneath the magnet 30 there isdisposed a metallic plate 31 of the same general shape and area.Disposed between this plate 31 and the lower face of the magnet 30 is asheet of fiber or insulation 32. At its forward edge the plate 31 isprovided with upstanding spaced ears 33 and 34 formed integrallytherewith, and having a gap therebetween at the center of the forwardedge of the plate 31. Disposed back of the ears 33 and 34 are a pair ofU- 95 shaped pole pieces 35 and 36 located with their bases facing awayfrom each other and with their respective legs extending toward eachother. The legs 37 and 38 of these polo pieces 35 and 36 have parallelfaces and are spaced apart a given distance back of the gap formedbetween the cars 33 and 34 above mentioned. The other legs 39 and 40 ofthese pole pieces 35 and 36 are tapered and their outer ends are smalland lie closely adjacent each other but parallel to form a small gaptherebetween much smaller than the gap or distance between the legs 37and 38. These pole pieces are held in position by means of screwspassing through the legs 37 and 38 and headed into a plate 41 ofnon-magnetic material lying back of the other side of the face of theselegs. The other ends of these screws are engaged by lock nuts lyingagainst the opposite faces of the ears 33 and 34. A shield plate 42 ofnon-magnetic material is held between the lock nuts and in front of theears 33 and 34. The plate 41 has a hole in its center in line with thegap between the legs 37 and 38 to permit of the passage of the end ofthe vibrating rod 21. The outer end of this rod will lie very close tothe gap between the legs 39 and 40 and because the magnetic field acrossthis gap is very intense the efiect of the vibration of the rod thereonis to make the field variations very sensitive. The horse-shoe magnet 30is held in position against the pole pieces merely by reason of themagnetic pull. Within the pole pieces, the magnetic coil 23 is disposedand lies snugly therein but is not fastened in place. Wires 43 and 44leading from the coil 23 are fastened to an insulating block 45 disposedloosely within the horse-shoe magnet back of the coil 23. This block 45has a central screw which passes through holes in the sheets 32, theplate 31 and the brass container 46 to engage the lower bar 13 and isheld by nuts 47 and 48 in position on the bar 13 and within thecontainer 46. A soft pad of rubber 49 lies within the brass containerbetween the ends of the screws connected to the plate 41 and the endwall of the container or box 46. This pad 49 has a hole therein topermit of the passage of the rod 21, and acts as a damper of vibrations.

The wires 50 and 51 connected to terminal clips 52 and 53 on the block45 pass through a hole in the plate 31 and on their othcr ends areprovided with tips to connect to any suitable electrical device such asan audio frequency amplifier.

Operation 0,1 the device When the strings of the instrument are bowed orotherwise vibrated to produce simple melody vibrations or complicatedones representing harmonies, these vibrations are transmitted to thebridge 18. This in turn is set into vibration and these are transmittedto the transmitting member or rod 21. The sensitivity of this red 21 tobeing vibrated is to some extent dependent upon the tension set uptherein by the adjustment through the intermediary of the cat-gutflexible member 24 which can be adjusted in the manner above described.This adjustment also positions the rod with respect to the magnet polepieces.

The magnetic field into which the end of the rod 21 extends is strongbut is particularly so near the outer end of the rod 21 and between thelegs 39 and 40 where the field is very concentrated and the slightestvibration of the end of the rod 21 closely adjacent to the gap betweenthese two legs causes a strong and very sensitive variation in themagnetic field which sets up, in the usual manner strong and verysensitive variations in the current in the coil 23 which are sent outover the wires 50 and 51 to the audioamplifier and properly magnified tobe reproduced on a loud speaker or other device. Thus the vibration ofthe strings 16 can be strongly and with extreme accuracy amplified sothat the resultant volume is equal to that of several stringedinstruments instead of to one. By utilizing this arrangement, a smallorchestra of stringed instruments can be amplified to equal a muchlarger one.

In other words, the stringed instruments not only generate airvibrations as usual but set up very strong and sensitive electricalvibrations which are amplified many times if desired. Severalinstrmnents can be connected up to the same audio amplifier so that oneloud-speaker can send forth the combined instrumental effects of theseveral instruments.

It is to be distinctly understood that when we speak of stringedinstruments of the violin type we mean to include such instruments asViolas, cellos, bass viols, mandolins, banjos, and otherstringedinstruments.

The device is simple, compact. and can be readily adjusted so that theutmost sensitivity of the vibratory parts can be obtained without anytrouble on the part. of the musician. When the vibrator has once beenadjusted, the musician plays as usual and has nothing further to concernhim except his playing.

While 1 have described our improvement in detail and with respect to apreferred form thereof, I do not desire to be limited to such details orform since many changes and modifications may be made and the inventionembodied in other forms Without departing from the spirit and scope ofthe invention in its broader aspects. Hence I desire to cover allmodifications and forms coming within the language or scope of any oneor more of the appended claims.

V7 hat I claim as new and useful, and dcsire to secure by LettersPatent, is,

1. A musical instrument of the violin type having a string and a bridgeconnected thereto, a magnetic unit mounted on the instrument, polepieces on said unit having a pinrality of gaps of different span, avibratory armature extending between one gap and lying closely adjacenta snialler gap at its out er end, and means connecting the armature tothe bridge.

2. A musical instrument of the violin type having a string and a bridgeconnected thereto, a magnetic unit mounted on the instrument, polepieces on said unit havin a plurality of gaps of different span, a viratory armature extending between one gap and lying closely adjacent asmaller gap at its outer end, means connecting the armature to thebridge, and means to adjust the armature with respect to one of thegaps.

3. A musical instrument of the type described, comprising a string to bevibrated, an electrical unit having a magnetic field and mounted on saidinstrument, means to transmit the vibration of the string to the unitand translate them into electrical current variations therein, and meansto independently adjust the vibration transmitting means to regulate thesensitivity of the device.

4. A musical instrument of the violin type comprising a string to bevibrated, an elect-rical unit having a magnetic field and mounted onsaid instrument, an armature lying in said magnetic field and responsiveto the vibration of said string, and means to independently adjust thearmature and regulate the sensitivity of the device.

5. A musical instrument of the violin type comprising a string to bevibrated, an electrical unit having a magnetic field and mounted on saidinstrument, an armature lying in said magnetic field and responsive tothe vibrations of said string, and means connected to said armatureintermediate its length between the electrical unit and the string toadjust the tension in the armature and regulate the sensitivity of thedevice.

(3. A musical instrument of the violin type comprising a string to bevibrated, a bridge on the violin supporting said string, an electricalunit having a magnetic field and mounted on said instrument, an armaturehaving a portion lying in said magnetic field and extending therefromand connected directly to said bridge, and adjustable means connected tosaid armature intermediate the electrical unit and said bridge to placethe armature under variable tension to regulate the sensitivity of thedevice.

In testimony that I claim the invention above set forth, I afiix mysignature hereto.

GEORGE EISENBERG.

